Adds type definitions for RollupWatcher events.

[NotWoods]

This PR contains:

• bugfix
• feature
• refactor
• documentation
• other

Are tests included?

• yes (bugfixes and features will not be merged without tests)
• no

Breaking Changes?

• yes (breaking changes will not be merged unless absolutely necessary)
• no

List any relevant issue numbers:

Description

Updated version of #3075 by @MicahZoltu
Closes #3075

The type information is extracted from /src/watch/index.ts@master , someone should double check that I got it all right. I'm new to rollup and have never actually used any of this stuff, but when I tried to I ran into the problem of there being no useful type information which caused me to have to read source code. Rather than having everyone suffer like I did, I decided to create a PR to resolve the issue.

[codecov]

Codecov Report

Merging #3302 into master will increase coverage by 0.04%.
The diff coverage is 85.71%.

@@            Coverage Diff             @@
##           master    #3302      +/-   ##
==========================================
+ Coverage   93.17%   93.22%   +0.04%     
==========================================
  Files         172      172              
  Lines        6041     6038       -3     
  Branches     1801     1801              
==========================================
  Hits         5629     5629              
+ Misses        221      218       -3     
  Partials      191      191

Impacted Files	Coverage Δ
src/rollup/index.ts	96.96% <ø> (ø)	⬆️
src/utils/PluginContext.ts	100% <100%> (ø)	⬆️
src/utils/deconflictChunk.ts	100% <100%> (ø)	⬆️
src/watch/index.ts	85.32% <100%> (ø)	⬆️
cli/run/watch.ts	43.58% <66.66%> (+1.61%)	⬆️

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[lukastaegert]

Looks good to me, except about the FATAL event, which is not really your doing but would be nice to clean up with this PR.
Also your definition of the TypedEventEmitter got me thinking if it could not be a way forward for fixing our dependency on the Node types (that are causing a lot of headaches for some) to just repeat the types we depend on in types.d.ts. To my knowledge, this would only be Buffer. But definitely something for a separate PR.

[lukastaegert]

Thanks

[shellscape]

🚢 it